The present invention relates to a new and distinctive pumpkin variety, designated ZYD5B. There are numerous steps in the development of any novel, desirable plant germplasm. Plant breeding begins with the analysis and definition of problems and weaknesses of the current germplasm, the establishment of program goals, and the definition of specific breeding objectives. The next step is selection of germplasm that possess the traits to meet the program goals. The goal is to combine in a single variety or hybrid an improved combination of desirable traits from the parental germplasm. These important traits may include higher yield, resistance to diseases and insects, tolerance to drought and heat, and better quality.
Choice of breeding or selection methods depends on the mode of plant reproduction, the heritability of the trait(s) being improved, and the type of cultivar used commercially (e.g., F1 hybrid, variety, etc.). For highly heritable traits, a choice of superior individual plants evaluated at a single location may be effective, whereas for traits with low heritability, selection should be based on mean values obtained from replicated evaluations of families of related plants. Popular selection methods commonly include pedigree selection, modified pedigree selection, mass selection, and recurrent selection.
The complexity of inheritance influences choice of the breeding method. Backcross breeding is used to transfer one or a few favorable genes for a highly heritable trait into a desirable cultivar. This approach has been used extensively for breeding disease-resistant cultivars. Various recurrent selection techniques are used to improve quantitatively inherited traits controlled by numerous genes. The use of recurrent selection in self-pollinating crops depends on the ease of pollination, the frequency of successful hybrids from each pollination, and the number of hybrid offspring from each successful cross.
Each breeding program should include a periodic, objective evaluation of the efficiency of the breeding procedure. Evaluation criteria vary depending on the goal and objectives, but should include gain from selection per year based on comparisons to an appropriate standard, overall value of the advanced breeding lines, and number of successful cultivars produced per unit of input (e.g., per year, per dollar expended, etc.).
Promising advanced breeding lines are thoroughly tested and compared to appropriate standards in environments representative of the commercial target area(s). The best lines are candidates for new commercial cultivars; those still deficient in a few traits are used as parents to produce new populations for further selection.
These processes, which lead to the final step of marketing and distribution, usually take from ten to 30 years from the time the first cross is made. Therefore, development of new cultivars is a time-consuming process that requires precise forward planning, efficient use of resources, and a minimum of changes in direction.
A most difficult task is the identification of individuals that are genetically superior, because for most traits the true genotypic value is masked by other confounding plant traits or environmental factors. One method of identifying a superior plant is to observe its performance relative to other experimental plants and to a widely grown standard cultivar. If a single observation is inconclusive, replicated observations provide a better estimate of its genetic worth.
The goal of plant breeding is to develop new, unique and superior pumpkin varieties and hybrids. The breeder initially selects and crosses two or more parental lines, followed by repeated selection, producing many new genetic combinations. The breeder can theoretically generate billions of different genetic combinations via crossing, selfing and mutations. The breeder has no direct control at the cellular level. Therefore, two breeders will never develop the same line, or even very similar lines, having the same pumpkin traits.
Each year, the plant breeder selects the germplasm to advance to the next generation. This germplasm is grown under unique and different geographical, climatic and soil conditions, and further selections are then made, during and at the end of the growing season. The varieties which are developed are unpredictable. This unpredictability is because the breeder""s selection occurs in unique environments, with no control at the DNA level (using conventional breeding procedures), and with millions of different possible genetic combinations being generated. A breeder of ordinary skill in the art cannot predict the final resulting lines he develops, except possibly in a very gross and general fashion. The same breeder cannot produce the same variety twice by using the exact same original parents and the same selection techniques. This unpredictability results in the expenditure of large research monies to develop superior new pumpkin varieties.
The development of commercial pumpkin hybrids requires the development of varieties, the crossing of these varieties, and the evaluation of the crosses. Pedigree breeding and recurrent selection breeding methods are used to develop varieties from breeding populations. Breeding programs combine desirable traits from two or more varieties or various broad-based sources into breeding pools from which varieties are developed by crossing and selection of desired pheno-types. The new varieties are crossed with other varieties and the hybrids from these crosses are evaluated to determine which have commercial potential.
Pedigree breeding is used commonly for the improvement of both self-pollinating and cross-pollinating crops. Two parents which possess favorable, complementary traits are crossed to produce an F1. An F2 population is produced by selfing one or several F1""s or by intercrossing two F1""s (sib mating). Selection of the best individuals is usually begun in the F2 population; then, beginning in the F3, the best individuals in the best families are selected. At an advanced stage of inbreeding (i.e., F6 and F7), the best lines or mixtures of phenotypically similar lines are tested for potential release as new cultivars.
Mass and recurrent selections can be used to improve populations of either self- or cross-pollinating crops. A genetically variable population of heterozygous individuals is either identified or created by intercrossing several different parents. The best plants are selected based on individual superiority, outstanding progeny, or excellent combining ability. The selected plants are intercrossed to produce a new population in which further cycles of selection are continued.
Backcross breeding has been used to transfer genes for a simply inherited, highly heritable trait into a desirable homozygous cultivar or inbred line which is the recurrent parent. The source of the trait to be transferred is called the donor parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., cultivar) and the desirable trait transferred from the donor parent. After the initial cross, individuals possessing the phenotype of the donor parent are selected and repeatedly crossed (backcrossed) to the recurrent parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., cultivar) and the desirable trait transferred from the donor parent.
Descriptions of other breeding methods that are commonly used for different traits and crops can be found in one of several reference books (e.g., Allard, 1960; Simmonds, 1979; Sneep et al., 1979; Fehr, 1987, Basset, 1986).
Proper testing should detect any major faults and establish the level of superiority or improvement over current cultivars. In addition to showing superior performance, there must be a demand for a new cultivar that is compatible with industry standards or which creates a new market. The introduction of a new cultivar will incur additional costs to the seed producer, the grower, processor and consumer; for special advertising and marketing, altered seed and commercial production practices, and new product utilization. The testing preceding release of a new cultivar should take into consideration research and development costs as well as technical superiority of the final cultivar. For seed-propagated cultivars, it must be feasible to produce seed easily and economically.
Once the varieties that give the best hybrid performance have been identified, the hybrid seed can be reproduced indefinitely as long as the homogeneity of the parent is maintained. A single-cross hybrid is produced when two varieties are crossed to produce the F1 progeny. Much of the hybrid vigor exhibited by F1 hybrids is lost in the next generation (F2).
Pumpkin is an important and valuable crop. Thus, a continuing goal of plant breeders is to develop stable, high yielding pumpkins that are agronomically sound. The reasons for this goal are obviously to maximize the total yield and quality produced on the land used. To accomplish this goal, the pumpkin breeder must select and develop pumpkin plants that have the traits that result in superior varieties and hybrids.
According to the invention, there is provided a novel pumpkin variety, designated ZYD5B. This invention thus relates to the seeds of pumpkin variety ZYD5B, to the plants of pumpkin variety ZYD5B and to methods for producing a pumpkin plant produced by crossing the variety ZYD5B with itself or another pumpkin variety. This invention further relates to hybrid pumpkin seeds and plants produced by crossing the variety ZYD5B with another pumpkin variety.
Pumpkin variety ZYD5B is a winter pumpkin of the species pepo with superior characteristics. Pumpkin variety ZYD5B was developed in two steps: (1) by creation of a recurrent parent and (2) by backcrossing disease resistance and bush habit into this recurrent parent.
(1) The recurrent parent was created by selecting open pollinated fruit in an isolation of Howden pumpkin and then using single plant pedigree selection to develop true breeding lines. Two closely related lines were developed that were involved in the backcrossing. Recurrent parent D13 was developed by selecting a single open pollinated fruit from the isolation and then selfing for 5 generations. Recurrent parent D5 was developed the same way except that another selection was chosen in the second self generation, and this was selfed for one additional generation.
(2) The donor of the Zucchini Yellow Mosaic Virus (ZYMV) resistance, Powdery Mildew (PM) resistance, and bush habit was a gray zucchini summer squash designated ZY5. The initial cross of this parent to pumpkin was made to an individual plant of a segregating population designated QBDNTt2. The first cross to the described recurrent parent was made to D13. There were 3 additional successive backcrosses, these being to D5. Six generations of single plant pedigree selection were made before the first open pollinated cage increase. Plants resistant to ZYMV and PM and having a bushy habit were selected at each segregating generation.